In 1986 Reinhard reported finding ruins of a ceremonial stone circle at the summit of Illakata, at over 14,000 feet one of the tallest mountains feeding runoff to the Nasca drainage system. Along with other traces of ritual activity at the top of Nasca watersheds, the discovery led him to propose that one of the main purposes of the Nasca lines was related to the worship of mountain deities, including Cerro Blanco, because of their connection to water.

Recent research has bolstered the hypothesis. In the highlands farther north, where wild vicuņas wander near the headwaters of the Palpa River, I joined Reindel and his team on a scramble to the top of a sacred mountain known locally as Apu Llamoca. (In the indigenous language, apu is the word for "deity.") At the summit of this dark volcanic dike, Reindel showed me a worship circle with ceramic potsherds the team had found in 2008 and nearby, a semicircular structure almost exactly like the one Reinhard had reported finding on Illakata.

For the Nasca-Palpa Project researchers, however, the real epiphany connecting Nasca sacred rituals to water worship occurred in 2000, on the trapezoid that dominates the desolate plateau near the village of Yunama. The archaeologists had frequently noticed large, man-made mounds of stones at the end of such trapezoids, which they suspected were ceremonial altars. As Reindel excavated his way through one mound, uncovering smashed potsherds, crayfish shells, vegetable remains, and other relics that clearly represented ritual offerings, he came upon fragments of a large seashell of the genus Spondylus, distinctive for its creamy, coral-like hues and spiky outer surface. It appears in the coastal waters off northern Peru only during El Niņo events and is thus associated with the arrival of rainfall and agricultural fertility.

"The Spondylus shell is one of the few items of Andean archaeology that has been well studied," Reindel says. "It's a very important religious symbol for water and fertility. Like incense in the Old World, it was brought from far away and is found in specific contexts, such as funerary objects and on these platforms. It was connected in certain activities to praying for water. And it's clear," he adds, "in this area, water was the key issue."

Ultimately, all those offerings and prayers went unanswered.

In 2004, at a site called La Tiza in the southern Nasca region, overlooking the dry Aja River, archaeologist Christina Conlee made a grim discovery while excavating a Nasca tomb. The first part of the skeleton to emerge from the dirt was not the skull, but the neck bones. "We could see the vertebrae sitting on top," Conlee told me. "The person was seated, with arms crossed and legs crossed, and no head."